20 | New Scientist | 24 October 2020WildlifeOdd penis shape
helps thwart rivalsCOMPLEX penis bones capable of
removing a rival’s semen could be
a way for males to ensure their
paternity with a long-term mate.
The baculum bone, found in the
penis of most mammals, sets the
shape of the penis tip and varies
widely in form across species, says
Charlotte Brassey at Manchester
Metropolitan University, UK. We
are one of a few primate species to
have evolved this bone away.Sun-powered box
pulls water from airA DEVICE that can extract water
from almost dry air using heat
from sunlight could help provide
a sustainable source of water in
remote areas that lack electricity.
Alina LaPotin at the
Massachusetts Institute of
Technology and her colleagues
developed the apparatus. It
contains a material called a
zeolite, which takes up water
vapour from the air at night.
During the day, heat from the sun
hits a solar collector and drives
the release of the water from the
material so it is suitable for use.
Because the zeolite is very
porous and has a large internal
surface area, it can adsorb the tiny
quantities of water held in almost
dry air, says LaPotin. Modelling
based on initial tests of her team’s
device predicts it could produce
water from air with a relative
humidity as low as 20 per cent –Technology^ EvolutionIVORY COAST, named for its
elephants, had one of the largest
populations of the animals in
West Africa. But now they are
in rapid decline.
Sery Gonedelé Bi at the University
Félix Houphouët-Boigny in Abidjan,
Ivory Coast, and his team surveyed
25 protected forest areas across the
country between 2011 and 2017.
They also analysed media reports
and records of conflict between
humans and elephants.
From this, the researchers
estimate that there are 225 forest
elephants left in Ivory Coast, a fall
of 86 per cent since a 1994 survey.
Estimates suggest that about a
century ago, the forest elephants
there numbered between 3000
and 5000, says Gonedelé Bi.
Based on dung counts, the
team confirmed the presenceof elephants in only four of the
25 protected forest areas they
checked. Habitat degradation is
a likely driver of the decline.
The team found that of the
360,000 hectares the 25 protected
forests cover, 71 per cent of this has
been cleared, mostly for growing
cocoa, says Gonedelé Bi. More than
half of the areas have been totally
lost to farms and settlements
(PLoS One, doi.org/fdm6).
Previous analysis has shown that
an estimated 265,000 hectares of
forest are cleared in Ivory Coast
every year, the highest deforestation
rate in sub-Saharan Africa.
The researchers believe that
without immediate action to
safeguard still-existing populations,
such as ranger patrols and law
enforcement, forest elephants will
go extinct in Ivory Coast. Donna LuIconic elephant population
on the brink of extinction
Brassey’s team used X-rays to
compare the bacula of 82 species,
including dogs, wolves and otters,
and concluded that the bone
shape may have a role in “post-
copulatory sexual competition”.
When females mate with more
than one male during the same
fertility cycle, the sperm of those
males compete to fertilise the few
available eggs. The design of the
penis tip could displace sperm
already in the reproductive tract,
clearing the way for the new male
(Proceedings of the Royal Society B,
doi.org/fdnf). The honey badger’s
baculum (pictured) even looks like
an ice cream scoop, says Brassey.
It really seems “designed to scoop
out other sperm”.
The most complex bacula were
found in animals that are socially
monogamous, meaning they tend
to pair for an extended period.
However, many such females mate
outside their “couple”, so the bone
shapes may have evolved for
males to ensure paternity, says
Brassey. Christa Lesté-Lasserrelevels seen in deserts. Existing
atmospheric water harvesting
devices, such as fog harvesting
and dewing systems, only work
at relative humidity levels of
at least 50 per cent.
Fog harvesting also has the
disadvantage of being limited
to areas with fog, and dewing
systems need to consume a lot
of energy to power refrigeration
systems that cool air below its
dew point, she says.
The box-shaped solar device
is made of acrylic, aluminium
and copper, and weighs about
7 kilograms. During tests, it was
able to produce 0.77 litres of water
each day for every square metre of
solar collector (Joule, doi.org/fdnj).
LaPotin says her team is
investigating ways to increase
the amount of water that can
be adsorbed by the material
inside the device, to increase its
efficiency further. “New materials
are being developed which have
a higher uptake,” she says.
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